Reference is first made to FIG. 1 where a handlebar/stem/head tube/head set/fork portion of a somewhat traditional prior art bicycle is shown to provide a foundation for the terminology used herein and to provide an understanding of the state of the art leading into the present invention. Each major element is identified to familiarize with common components. It can be seen that the frame of the bicycle includes a head tube assembly at its forward-most end. The head tube assembly includes the head tube, the upper and lower head sets, and the fork including its steering tube. The head tube is slightly tilted from vertical, but to satisfy the needs of this description will be referred to as “vertical”. Readers should understand that “vertical” as used herein is meant to convey “substantially vertical”, and “horizontal” as used herein is meant to convey “substantially horizontal”. The head tube assembly includes two sets of internal ball bearings; the upper head set adjacent the top of the head tube and the lower head set at the base of the head tube.
The fork includes a downwardly extending yoke for rotationally receiving the bicycle's front wheel. The yoke is integrally and rigidly formed with the steering tube, together forming the fork. The steering tube projects vertically upwardly and extends through the head tube, and is held by the head tube through the upper and lower head sets so that the fork is rotational relative to the head tube and frame about the vertical center axis of the steering tube. The uppermost end of the steering tube protrudes above the head tube.
The horizontally disposed handlebar is engaged to the uppermost end of the steering tube by the stem, which includes a horizontal hole for receiving the handlebar and a vertical hole for receiving the upper end of the steering tube. When properly affixed, the handlebar, stem, and fork become a single rigid member which is side-to-side rotational relative to the head tube and frame about the vertical center axis of the steering tube to effect steering of the bicycle.
Handlebars have long been available in numerous shapes to optimally position the grips at the outer ends, which the rider grasps during riding. While the traditional bicycle of FIG. 1 shows a traditional stem that positions the handlebar several inches forward of the steering tube, handlebars have long been available for positioning the grips, in both height and forward-backward position, wherever is most comfortable for the rider. But recent efforts have found that grip position alone is not sufficient to optimize steering control. Control is now realized to be optimized as the distance between the handlebar and the steering tube (Stem Offset), and the proximity of the handlebar to the head tube (Stem Height) is decreased.
In response to these findings, stems are recently available in numerous configurations to attempt to minimize Stem Offset and Stem Height. Stems are now available which can position the centerline of the handlebar as close as 35 MM from the centerline of the steering tube at minimum Stem Height, or stems are now available which can position the centerline of the handlebar as close as 10 MM from the centerline of the steering tube when Stem Height is sacrificed. But to date, no arrangement is available for minimizing both Stem Offset and Stem Height.